The invention relates to a method for detecting a malfunction of a sensor for measuring an analyte concentration in vivo, wherein a series of measuring signals is produced by means of the sensor, and a value of a noise parameter is continually determined from the measuring signals, the noise parameter indicating how severely the measurement is impaired by interference signals.
A method of this type is described in U.S. Patent Application Publication No. 2009/0076361 A1, Kamuth et al., published Mar. 19, 2009. In the known method, a noise parameter is compared to a pre-determined threshold value. The value of the noise parameter exceeding the threshold value leads to the conclusion that there is a malfunction.